Plot

An hour later, Toad arrives at the castle with a camera-wielding Lakitu, both perplexed about the disappearance of their friends. As the two come to the castle, a panicked Blue Toad rushes out and exclaims that Mario is missing. He also states that Bowser has trapped Peach and the other Toads inside the castle paintings. Toad agrees to help find his friends.

SPOILER ALERT! The following contains secrets about this game. Beware!

After obtaining a few Power Stars, Toad opens the door to Petey Piranha's lair, where Mario is being held hostage. After getting through a small course, Toad confronts Petey Piranha and defeats him by attacking his three Piranha Plant guards and then attacking his head three times. As Petey flies away in defeat, he drops the key to Mario's door, which unlocks Mario and allows him to be played as.

As more Power Stars are obtained, Mario enters King Boo's lair, where Luigi is being held hostage. Mario explores the terrain and comes to confront the ghostly ruler himself. The two engage in battle, which Mario wins by Ground Pounding his shadow. King Boo dissolves into thin air, dropping the key to Luigi's door and unlocking Luigi himself.

Luigi obtains more Power Stars and acesses Chief Chilly's lair, where the evil iceberg is holding Wario hostage. Once across a small ice course, Luigi confronts Chief Chilly and defeats him by smacking him three times into the water. As Chief Chilly melts in the water, he drops the key to Wario's door and unlocks him.

Once more, Wario obtains Power Stars and goes to Captain Syrup's lair, which is actually a giant battleship. Wario enters Syrup's quarters to face off with the greedy pirate herself. After being hit three times by Wario's Arm-Check move, she declares defeat and hands over the key to Waluigi's door, unlocking the final character to play as, Waluigi.

Towards the end, Mario goes to face Bowser in the final zone. After a long and gruesome fight, Mario defeats Bowser. The Koopa King declares defeat and leaves the game. Mario uses the Grand Power Star to fly away. As Mario lands in front of Peach's Castle, Toad, Luigi, Wario, and Waluigi join him and all watch as Peach comes out of the potrait on front of the castle. She thanks Mario and tells everybody to come in for cake. Toad stops to look at the sky but Peach calls him in and he joins everyone else. The credits roll and at the end the cake, with Peach, Mario, Luigi, Wario, Waluigi, and Toad figures is seen at the very end.

World 1 World 2 World 3 World 4 with 150 courses... MORE ARE COMING!!!